1. FIELD OF THE INVENTION
This invention relates to a mechanism for receiving electronic parts, e.g., IC chips, continuously transported by a conveyor belt and separating or dispensing them one at a time. The electronic parts separation mechanism in accordance with the present invention is particularly suitable to be used in a conveyor portion which is a downstream-most part of an apparatus for delivering electronic parts to a device for mounting them onto a substrate.
2. Description of the Prior Art
The above-mentioned electronic parts delivering apparatus conventionally includes a frame body, a stick holder which is attached to the frame body and which releasably holds a stick having an open outlet end and accommodating a plurality of electronic parts therein, a chute arranged in an inlined manner so as to slidably guide the electronic parts taken out from the open outlet end of the stick by a gravitational force, and a conveyor portion for receiving the electronic parts at the end of the chute and transporting them by a conveyor belt to a pick-up point. The electronic parts, which have been transported to the pick-up point on the conveyor belt, are picked-up there and are supplied to a device for mounting such electronic parts onto a substrate.
The electronic parts are dispensed by means of a separation mechanism to the pick-up point one at a time. The separation mechanism is known in the art in which a pair of pawl members are positioned above the electronic parts riding on the conveyor belt. The pawl members are arranged to alternately extend downwardly. Forward and rearward pawl members extend, respectively, in front of and behind a particular electronic part which is the one closest to the pick-up point on the conveyor, i.e., the first one of a series of the electronic parts. While the forward pawl member extends downwardly to engage the front surface of the first electronic part to thereby interfere with forward movement thereof, the rearward pawl member is positioned at its upper retracted position. Then, the rearward pawl extends between the first electronic part and a succeeding or second electronic part and, almost simultaneously, the forward pawl member is retracted to its upper position. Thus, the first electronic part is dispensed to the pick-up point by the moving conveyor belt, while the succeeding or second electronic part is prevented by the rearward pawl member from moving forward. At substantially the same time when the forward pawl member again extends downwardly from its upper or retracted position, the rearward pawl member retracts to its upper position to allow the succeeding or second electronic part to be advanced by the moving conveyor belt until the second electronic part comes in contact with the forward pawl member. Thus the second electronic part becomes the forward-most or new first electronic part. The above operations are repeated and the electronic parts are dispensed to the pick-up point one at a time.
It should be noted that electronic parts usually vary in length according to the number of pins involved therein and to manufacturing tolerance. Therefore, the prior art separation mechanism as mentioned above tends to cause jamming due to inadvertent engagement of the pawl members with the upper surfaces of the electronic parts. It may, therefore, be required to modify the operation or design of the separation mechanism when it is used for electronic parts of different length. However, this is very disadvantageous in view of manufacturing costs.
In order to eliminate the above problems, a separation mechanism has been proposed in which a rearward pawl member is designed to, when actuated, come into contact with the upper surface of the electronic part so as to urge it downwardly against the belt conveyor to thereby stop the electronic part.
This mechanism, however, has disadvantages in that the stability of actuation of the conveyor belt is influenced since the belt is subject to a pressing force tending to hold it upon actuation of the rearward pawl member. This force causes a decrease in speed of the belt and, in some extreme cases, stoppage of the belt.